Membrane

ABSTRACT

A membrane is suitable to be mounted on a polishing head of a chemical mechanical polishing apparatus and includes a main portion and an edge portion. The edge portion is located at an edge of the main portion, wherein a first included angle between the main portion and the edge portion is an obtuse angle.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The disclosure is related to a membrane, and in particular to a membrane suitable to be mounted on a polishing head of a chemical mechanical polishing apparatus.

2. Description of Related Art

Because the resolution of photolithography exposure increases along with the decrease in device size and the depth of field at exposure is reduced, the requirement to planarity of chip surface increases drastically. Thus, when performing the deep sub-micron process, the planarization of the chip then depends on the chemical mechanical polishing (CMP) process. The unique anisotropic polishing property of the CMP process is not only used for the planarization of the surface contour of the chip, but can also be applied in the fabrication of damascene structures of perpendicular and horizontal metal interconnections, the fabrication of shallow trench isolations in devices and the fabrication of advanced devices in the previous stage, and the fabrication of micro-electromechanical system planarization and the fabrication of flat displays, etc.

The CMP process mainly utilizes a reagent in the polishing slurry for generating a chemical reaction on the front side of the wafer to form a polishable layer. Further, with the wafer on the polishing pad, the protruding portions of the polishable layer are polished off by the mechanical polishing with the facilitation of abrasive particles in the polishing slurry. The chemical reactions and the mechanical polishing are then repeated to form a planar surface.

However, when a polishing head of a chemical mechanical polishing apparatus is placed on the polishing pad, a retainer ring of the polishing head presses against the polishing pad, causing the polishing pad to deform. When polishing the wafer, a protruding portion formed by deformation of the polishing pad exerts pressure on an edge of the wafer, making a polishing speed at the edge of the wafer too fast. The deformation of the polishing pad also causes polishing rates at some portions of the wafer to become slower. These phenomenon cause inferior planarity of the surface of the wafer after polishing.

SUMMARY OF THE INVENTION

The disclosure provides a membrane which effectively solves problems of non-uniform polishing rates.

The disclosure provides a membrane, suitable to be mounted on a polishing head of a chemical mechanical polishing apparatus. The membrane comprises a main portion and an edge portion. The edge portion is located at an edge of the main portion, wherein a first included angle between the main portion and the edge portion is an obtuse angle.

According to an embodiment of the disclosure, in the above membrane, a frame of the polishing head includes a frame main body and a retainer ring, the membrane is mounted on the frame main body, and the retainer ring surrounds and is connected to the frame main body, when the retainer ring presses against a polishing pad, the polishing pad in the retainer ring forms a protruding portion, a second included angle is formed between a planar portion of the polishing pad and the protruding portion, and the first included angle is, for example, substantially equal to the second included angle.

According to an embodiment of the disclosure, in the above membrane, an area within which the edge portion of the membrane operates is, for example, substantially equal to the area within which the protruding portion of the polishing pad is located.

According to an embodiment of the disclosure, in the above membrane, the second included angle is, for example, 90 degrees to 180 degrees.

According to an embodiment of the disclosure, in the above membrane, the first included angle is, for example, 90 degrees to 180 degrees.

According to an embodiment of the disclosure, in the above membrane, a material of the membrane is, for example, rubber.

According to an embodiment of the disclosure, in the above membrane, the main portion and the edge portion are, for example, integrally formed.

In light of the above, in the membrane provided by the disclosure, since the included angle between the main portion and the edge portion is an obtuse angle, pressure caused by the protruding portion of the polishing pad pressing against an edge of a substrate is effectively pre-released, thereby increasing uniformity of polishing rates at each position of the substrate, so that the substrate has better surface planarity after being polished.

In order to make the aforementioned and other objects, features of the disclosure comprehensible, embodiments accompanied with figures are described in detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the disclosure and, together with the description, serve to explain the principles of the disclosure.

FIG. 1 is a sectional axonometric drawing of a membrane according to an embodiment of the disclosure.

FIG. 2 is a schematic view of the membrane in FIG. 1 mounted on a polishing head of a chemical mechanical polishing apparatus.

DESCRIPTION OF EMBODIMENTS

FIG. 1 is a sectional axonometric drawing of a membrane according to an embodiment of the disclosure.

Please refer to FIG. 1, a membrane 100 is suitable to be mounted on a polishing head of a chemical mechanical polishing apparatus. The membrane 100 includes a main portion 102 and an edge portion 104. The edge portion 104 is located at an edge of the main portion 102. A material of the membrane 100 is, for example, rubber. The main portion 102 and the edge portion 104 are, for example, integrally formed.

A first included angle θ1 between the main portion 102 and the edge portion 104 is an obtuse angle. The first included angle θ1 is designed as an obtuse angle so that the edge portion 104 of the membrane 100 tilts upward, forming an object-containing space S between the edge portion 104 and an extending line EL of the main portion 102. According to the present embodiment, the first included angle θ1 is defined as an included angle between a longitudinal extending direction L1 of the main portion 102 and a longitudinal extending direction L2 of the edge portion 104. The longitudinal extending direction L1 and the longitudinal extending direction L2 respectively represent overall extending directions of the main portion 102 and the edge portion 104. The first included angle is, for example, from 90 degrees to 180 degrees.

According to the above embodiment, since the first included angle θ1 between the main portion 102 and the edge portion 104 is designed as an obtuse angle, the object-containing space S is formed between the edge portion 104 and the extending line EL of the main portion 102. The object-containing space S is able to contain a protrusion caused by deformation of a polishing pad, so that the membrane 100 effectively pre-releases the pressure caused by a protruding portion of the polishing pad pressing against an edge of a substrate.

FIG. 2 is a schematic view of the membrane in FIG. 1 mounted on a polishing head of a chemical mechanical polishing apparatus.

Please refer to both FIGS. 1 and 2. In a chemical mechanical polishing apparatus 200, a frame 204 of a polishing head 202 includes a frame main body 206 and a retainer ring 208, and the retainer ring 208 surrounds and is connected to the frame main body 206.

The membrane 100 is mounted on the frame main body 206 of the polishing head 202. Designs, materials, and functions of the membrane 100 have been described in detail in the embodiment shown in FIG. 1 and are hence not repeatedly described.

According to the present embodiment, a substrate for polishing is, for example, a wafer W. When polishing the wafer W, the polishing head 202 is used to place the wafer W on the polishing pad 210. The retainer ring 208 presses against the polishing pad 210, causing the polishing pad 210 in the retainer ring 208 to form a protruding portion 212. Therefore, a second included angle θ2 is formed between a planar portion 214 and the protruding portion 212 of the polishing pad 210, and the second included angle θ2 is an obtuse angle. The first included angle θ1 is substantially equal to the second included angle θ2, for example. According to the present embodiment, the second included angle θ2 is defined as an included angle between a longitudinal extending direction L3 of the planar portion 214 and a longitudinal extending direction L4 of the protruding portion 212 in FIG. 2. The longitudinal extending direction L3 and the longitudinal extending direction L4 respectively represent overall extending directions of the planar portion 214 and the protruding portion 212. The second included angle θ2 is, for example, from 90 degrees to 180 degrees. An area within which the edge portion 104 of the membrane 100 operates is substantially equal to the area within which the protruding portion 212 of the polishing pad 210 is located, for example. According to the above, the first included angle θ1 of the membrane 100 and an area within which the edge portion 104 of the membrane 100 operates are, for example, designed according to the second included angle θ2 of the polishing pad 210 and according to the area within which the protruding portion 212 of the polishing pad 210 is located.

According to the above embodiment, when the retainer ring 208 of the polishing head 202 presses against the polishing pad 210 and forms the protruding portion 212, since the included angle θ1 between the main portion 102 and the edge portion 104 of the membrane 100 is designed as an obtuse angle, the object-containing space S is formed between the edge portion 104 and the extending line EL of the main portion 102. The object-containing space S below the edge portion 104 of the membrane 100 is capable of containing the deformed portion of the wafer W caused by pressure from the protruding portion 212, thereby pre-releasing the pressure caused by the protrusion portion 212 of the polishing pad 210 pressing against the edge of the wafer W. Therefore, uniformity of polishing rates at each position of the wafer is increased, so that the wafer W has better surface planarity after being polished.

In light of the above, the membrane according to the above embodiment has at least the following features:

-   -   1. The membrane according to the above embodiment effectively         pre-releases the pressure caused by the protruding portion of         the polishing pad pressing against the edge of the substrate.     -   2. By utilizing the membrane according to the above embodiment,         uniformity of polishing rates of the wafer is increased, so that         the substrate has better surface planarity after being polished.

It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosure without departing from the scope or spirit of the disclosure. In view of the foregoing, it is intended that the disclosure cover modifications and variations of this disclosure provided they fall within the scope of the following claims and their equivalents. 

1. A membrane, suitable to be mounted on a polishing head of a chemical mechanical polishing apparatus, the membrane comprising: a main portion; and an edge portion, located at an edge of the main portion, wherein a first included angle between the main portion and the edge portion is an obtuse angle.
 2. The membrane as claimed in claim 1, wherein a frame of the polishing head comprises a frame main body and a retainer ring, the membrane is mounted on the frame main body, and the retainer ring surrounds and is connected to the frame main body, when the retainer ring presses against a polishing pad, the polishing pad in the retainer ring forms a protruding portion, a second included angle is formed between a planar portion of the polishing pad and the protruding portion, and the first included angle is substantially equal to the second included angle.
 3. The membrane as claimed in claim 2, wherein an area within which the edge portion operates is substantially equal to the area within which the protruding portion of the polishing pad is located.
 4. The membrane as claimed in claim 2, wherein the second included angle is from 90 degrees to 180 degrees.
 5. The membrane as claimed in claim 1, wherein the first included angle is from 90 degrees to 180 degrees.
 6. The membrane as claimed in claim 1, wherein a material of the membrane comprises rubber.
 7. The membrane as claimed in claim 1, wherein the main portion and the edge portion are integrally formed. 